A Fairy Tale Provides Inspiration for a New Weapon in the Battle Against the Cane Toad

For predators in Australia, the invasive cane toad is a tempting meal. The problem is that these toads are highly toxic—often killing large numbers of naive native species before they have a chance to adapt.

Conservationists there have tried everything from cat-food bait to toad smashing festivals to quell the spread of the cane toad hoards—all with limited success. But there is new hope: Conservationists inspired by an old fairy tale have developed an innovative new process to "teach" species about the dangers of eating toads.

The cane toad is a threat to many of Australia's native species. Image credit: Sam Fraser-Smith/Flickr

I was reading a modern version of 'Little Red Riding Hood' to my kids, and in that story Grandma sews raw onions into the wolf's stomach, so when the wolf wakes up he feels sick and refuses to eat another Grandma again. It dawned on me that if we could teach northern quolls to associate sickness with cane toads, we might have a way of conserving them.

The northern quoll—a rat-sized marsupial native to Australia—has been driven to extinction in many parts of the country. Now, with the cane toads advancing into one of the last quoll strongholds, a race is on to find a means of protecting the species.

Thanks to the invasive cane toad, the northern quoll is extirpated in much of Australia. Image credit: Wikimedia Commons

Dr. Webb, along with his colleagues Rick Shine and Stephanie O'Donnell, decided to take a cue from that crafty grandmother trapped in the wolf's stomach. By taking small cane toads—which do not have enough toxin to kill a quoll if consumed—and filling them with thiabendazole, a mildly toxic fungicide, the researchers were able to teach the marsupials to associate meals of invasive toads with nausea.

This training, called "conditioned taste aversion," worked. Quolls that were given the poisoned toad were much less likely to attack cane toads afterwards. Dr. Webb commented:

Our results show that this kind of approach works. If you can teach a predator that cane toads make you sick, then that predator will leave them alone afterwards. As a result, animals like quolls can survive in the wild even in a toad-infested landscape

The next step is to see if the process can be scaled to wild populations. If it does, conservationists might finally have a tool for fighting this devastating invasive species—which has defied all attempts at eradication.